Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• , extended π-surfaces [64] of TTF derivatives can have a stabilizing effect upon complexation. TTF (1) also forms inclusion complexes with neutral host molecules such as cyclodextrins (Figure 6). This complexation is mainly driven by the hydrophobic effect. α-Cyclodextrin (6) molecules encapsulate the

• TTF2+. This relatively straightforward concept of electrochemically triggered complexation and expulsion of the TTF molecule from different hosts forms the fundament for motion control in a variety of different MIMs. To illustrate how this redox-triggered complexation/decomplexation of pseudorotaxanes

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• binding sites offering multipoint interactions with a substrate for the effective complexation [13]. Calix[4]arenes and their thia analogues have many advantages over other macrocycles that are frequently used as synthetic receptors, such as cyclodextrins [14], cucurbiturils [15], and pillararenes [16

• displacement from aggregates, decorated by positive charged thiacalixarene macrocycles. This approach was used for macrocycles 10a,b and 12a,b as well. Primarily, the fundamental regularities of dye complexation with 10a,b and 12a,b were studied in detail. The stoichiometry of the EY–calixarene complexes was

• vesicles upon binding to ADP can be a result of a complexation-induced distortion of the calixarene cavity provoking thus perturbation of the PDA backbone. Conclusion For the first time new calix[4]arenes adopting a cone stereoisomeric form bearing two or four azide groups directly located at the

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• investigate their complexation behaviour with CB7. The goal was to explore the suitability of this approach, the possibility to fine-tune binding constants with different anchor groups and to provide BODIPYs with different absorption and emission wavelengths as well as pKa values of the aniline substituent

• have been previously reported for some BODIPYs substituted with diamines in the aniline meso-position, and the decreased quantum yields were ascribed to the loose-bolt effect [41][54][55]. Complexation with CB7 Addition of excess CB7 to the BODIPY dyes at low pH values, in which the dyes are fully

• of the dyes increased upon addition of CB7 (Figure 3). This result is in accordance with the anticipated anchor group mechanism leading to a complexation-induced protonation of the dye (Figure 1). It also suggests that the BODIPY core is not encapsulated in the macrocyclic cavity and that

Synthesis and characterization of π–extended “earring” subporphyrins

• Haiyan Guan,
• Mingbo Zhou,
• Bangshao Yin,
• Ling Xu and
• Jianxin Song

Beilstein J. Org. Chem. 2018, 14, 1956–1960, doi:10.3762/bjoc.14.170

• detected in the very low field region. This indicates that the Pd is inserted in the cavity of 3 with the deprotonation of both N-H and meso-H. Meanwhile all signals belong to aromatic hydrogens shifted to a slightly higher field region after the complexation with Pd, which reveals that the insertion of

• ,β′-diiodosubporphyrin and diboryltripyrrane via a Suzuki–Miyaura coupling and following oxidation. This “earring” subporphyrin’s cavity allows for complexation of Pd atom to form the corresponding Pd complex. The 1H NMR spectra of the compounds reveal that the aromatic ring current does not extend

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

• Tomoki Ogoshi,
• Tomohiro Akutsu and
• Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

• 1,4-dicyanobutane, the clouding points gradually decreased from 24 °C to 12 °C (Figure 3a). Formation of the de-threaded form by complexation between 3 and 1,4-dicyanobutane induced aggregation of the alkyl chain ring on the outside of the cavity. However, only a very minor change in the clouding

• point was observed upon addition of 1,4-dicyanobutane to an aqueous solution of 1 (Figure 3b, indicating that the hydrophobic/hydrophilic ratio did not change much by the host–guest complexation between 1 and 1,4-dicyanobutane because 1,4-dicyanobutane was hidden inside the hydrophilic pillar[5]arene

• Information File, Figure S7, orange peak β) of 1,4-dicyanobutane. Chemical structures of (a) tri(ethylene oxide)-substituted pillar[n]arenes (1, n = 5; 2, n = 6), (b) pseudo[1]catenane 3, (c) de-threaded form of 3 by complexation with 1,4-dicyanobutane, and (d) model compound 4. 1H NMR spectra of (a) model

Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH

• Femke Beiroth,
• Tomas Koudelka,
• Thorsten Overath,
• Stefan D. Knight,
• Andreas Tholey and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163

• comprising a lectin domain FimHL hosting the α-D-mannose-specific carbohydrate binding site and a pilin domain FimHP connecting the protein to the fimbrial shaft (Figure 2). Complexation of α-D-mannopyranoside ligands involves the entire mannoside glycon moiety whereas the aglycon portion sticks out of the

• sensitivity.) The bivalent ligand 5, on the other hand, seems to be sterically too demanding to allow good complexation with the carbohydrate binding site of FimH; mainly unspecific interactions with the surface of FimH were predicted in this case. Thus, synthesis of 5 was not undertaken. In contrast, the

• expected that it would be easier to photolabel peptides than FimH, after the failure with photolabeling of the model peptides we were hoping that labeling of FimH would be more successful, as our ligand was designed to bind to FimH. We reasoned that complexation of the photolabile mannoside 3 and FimH

Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene

• Jie Gao,
• Zhe Zheng,
• Lin Shi,
• Si-Qi Wu,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2018, 14, 1840–1845, doi:10.3762/bjoc.14.157

• applications of them [25][26][27][28]. In this work, we report a fluorescent IDA approach for detecting BPs quantitatively in not only buffer solution but also artificial urine (Scheme 2). The rationale behind the IDA approach is the strong and selective complexation of BPs by guanidinium-modified calix[5

• , we employed fluorescein (Fl) as the reporter dye according to our previously published result [26]. Fl of high brightness is strongly encapsulated into the GC5A cavity (Ka = 5.0 × 106 M−1), accompanied with a drastic complexation-induced fluorescence quenching (Ifree/Ibound = 37). Taken together

• recovery, offers the opportunity for fluorescence “switch-on” sensing of BPs. In general, fluorescent IDA could be operated at low μM or even nM concentrations, which is desirable with respect to sensing sensitivity. We tested the host–guest complexation of GC5A with a total number of 9 BP drugs clinically

Host–guest complexes of conformationally flexible C-hexyl-2-bromoresorcinarene and aromatic N-oxides: solid-state, solution and computational studies

• Rakesh Puttreddy,
• Ngong Kodiah Beyeh,
• S. Maryamdokht Taimoory,
• Daniel Meister,
• John F. Trant and
• Kari Rissanen

Beilstein J. Org. Chem. 2018, 14, 1723–1733, doi:10.3762/bjoc.14.146

• , aiding in the binding of polar guests such as N-oxides. Keywords: aromatic N-oxides; C–H···π Interactions; ditopic receptors; endo/exo complexation; host–guest chemistry; resorcinarenes; Introduction Resorcinarenes are macrocyclic compounds with a bowl-shaped cavity stabilised by circular

• encapsulation in the bowl-shaped upper rim (endo complexation) due to size complementarity between host cavity and guest shape, and are generally stabilised through multiple C–H···π interactions [26][27][28]. The cavity capacity to undergo induced conformational changes in response to the incorporation of

• , 1+BrC6 indicates either from combination of guest 1 and BrC6 or exo complex while 1@BrC6 denotes the endo complexation process. However, considering the host flexibility, ‘Δ’ (Table 1), which is the measure of difference between centroid-to-centroid distances of opposite host aromatic rings, guests

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• sulfides. The reaction is proposed to proceed via formation of a copper complex by coordination of the copper to the sulfur and nitrogen atoms of the disulfide. The complexation is accompanied by an increase in the sulfur–sulfur bond length and assists the cleavage of this bond by the attacking nucleophile

• (II) iodide catalyst enables the use of both diaryl and dialkyl disulfides to provide the corresponding masked β-hydroxy sulfides. The proposed mechanism is depicted in Scheme 34 [69]. The reaction commences with the complexation/activation of the disulfide by the CuI catalyst. The nucleophilic alkene

A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene

• Liu-Pan Yang,
• Song-Bo Lu,
• Arto Valkonen,
• Fangfang Pan,
• Kari Rissanen and
• Wei Jiang

Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134

• types of organic cations hosted by TA4 (6+–10+) were tested with ZB4. Most of these guests can indeed be complexed. But there are some exceptions. Changing the core quaternary ammonium structure of 3+ completely shuts down the binding, because no obvious complexation-induced shifts were detected in the

• 1:1 mixture of ZB4 with 4+ or 5+ (Figures S1 and S2 in Supporting Information File 1). This indicates the importance of the core quaternary ammonium ions in the host−guest complexation. All other guests can be encapsulated in the cavity of ZB4, and significant chemical shifts on both the guests and

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• is confirmed to depend on a fine balance between different factors, namely Coulomb and π···π interactions, and steric effects. The importance of a compromise between these factors for the complexation into calixresorcinarenes has been recently assessed [42]. Moreover, in analogy with the bahavior

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• these catalysts confirmed the necessary role of the calixarene skeleton in phase-transfer catalysis by preorganizing and orienting the amide groups properly to favor the complexation of Na+ cations. The effect of the ester group in the substrate and other parameters on the reaction were also

A three-armed cryptand with triazine and pyridine units: synthesis, structure and complexation with polycyclic aromatic compounds

• Claudia Lar,
• Adrian Woiczechowski-Pop,
• Attila Bende,
• Ioana Georgeta Grosu,
• Natalia Miklášová,
• Elena Bogdan,
• Niculina Daniela Hădade,
• Anamaria Terec and
• Ion Grosu

Beilstein J. Org. Chem. 2018, 14, 1370–1377, doi:10.3762/bjoc.14.115

• libraries [2][25][34][35]) allowed accessing of more sophisticated architectures. In a previous work [32] we reported the formation of a host–guest complex between a cryptand having pyridine units in the bridges and 1,3,5-triphenylbenzene caps (1, Figure 1). Surprisingly, no complexation ability of cryptand

• [32] revealed its selective absorption ability for N2 and CO2 in the solid state. The low complexation ability of cryptand 1 in solution for aromatic guests is due to the unfavorable conformation of the 1,3,5-triphenylbenzene central units in which the peripheral aromatic rings are twisted with

• respect to the central benzene ring. In such twisted conformations there is a remarkable steric hindrance between the ortho hydrogen atoms of the central benzene ring and the ortho' hydrogen atoms of the peripheral aromatic units. These conformations are not favorable for a complexation of aromatic guests

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

• Anna Czarnecka,
• Emilia Kowalska,
• Agnieszka Bodzioch,
• Joanna Skalik,
• Marek Koprowski,
• Krzysztof Owsianik and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

• patent literature [44]. Benzophenones were also reduced to diarylmethanes using supercritical iPrOH at 350 °C [1], BF3·OEt2/H2O [33] and PhSiH3/MoCl2O2(H2O)2 [45]. The reductive deoxygenation reactions of diarylmethanols proceed via carbocationic species, which are formed by protonation or complexation

• diarylmethanes. Most probably, electron-donating groups on aryls facilitate both Zn complexation and stabilization of the intermediate carbocationic species formed. Conclusion In summary, a new example of the selective functional group transformation of diarylmethanols (Ar1Ar2CH(OH)) to diarylmethanes (Ar1Ar2CH2

An uracil-linked hydroxyflavone probe for the recognition of ATP

• Márton Bojtár,
• Péter Zoltán Janzsó-Berend,
• Dávid Mester,
• Dóra Hessz,
• Mihály Kállay,
• Miklós Kubinyi and
• István Bitter

Beilstein J. Org. Chem. 2018, 14, 747–755, doi:10.3762/bjoc.14.63

• a uracil nucleobase to the known 4’-dimethylamino-hydroxyflavone fluorophore. Results: The complexation of this scaffold with ATP is already known. The complex is held together by stacking and electrostatic interactions. To achieve multi-point recognition, we designed the uracil-appended version of

• . Conclusions: The first, uracil-containing fluorescent ATP probe based on a hydroxyflavone fluorophore was synthesized and evaluated. A selective complexation with ATP was observed and a ratiometric response in the excitation spectrum. Keywords: ATP sensing; base-pairing; fluorescent probes; 3-hydroxyflavone

• interactions, which prompted us towards the synthesis of UHF by click chemistry. Fluorescence spectroscopy revealed a selective complexation with ATP with an association constant of around 2∙104 M−1 and a ratiometric response in the excitation spectrum. Results and Discussion Structure and calculations Based

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

• Katharina Hiebler,
• Georg J. Lichtenegger,
• Manuel C. Maier,
• Eun Sung Park,
• Renie Gonzales-Groom,
• Bernard P. Binks and
• Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

• economical aspects [13]. One possibility to prepare heterogeneous transition metal catalysts is to immobilise palladium directly on a solid support such as activated carbon [14], zeolites [15], modified silica [16][17][18] or molecular sieves [19] to name but a few. Another option is the complexation of

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst

• Longcheng Hong,
• Sebastian Ahles,
• Andreas H. Heindl,
• Gastelle Tiétcha,
• Andrey Petrov,
• Zhenpin Lu,
• Christian Logemann and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48

• -dimethyl-5,10-dihydroboranthrene (A in Scheme 1), developed in our group [13]. A complexation was confirmed by a high field shift of the aromatic protons compared with the non-coordinated catalyst A. As shown in Scheme 2, besides 1,2-diphenylhydrazine (1d), most of the Lewis bases including monodentate 1a

• optimized procedure, BBr3 was used to replace BCl3 and the dimerization reaction can be carried out in a normal Schlenk tube without any solvent. The methylation reagent, AlMe3 can be added in situ followed by the complexation with pyridazine. The one-pot procedure is also applicable to the synthesis of

• reactions were carried out and the results showed that the catalytic activity of the complex in IEDDA reactions depended on its performance in ligand exchange with the diazine substrates. Experimental Complexation of 5,10-dimethyl-5,10-dihydroboranthrene with Lewis bases: In the glovebox, 5,10-dimethyl-5,10

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• derivatives were prepared from 3 in order to examine their host–guest properties by ESI mass spectrometry and NMR spectroscopy. Some tetraoxaadamantanes were also examined in this way. For example, compound 30 (Figure 1) was found to have a particular affinity for complexation with choline [26][36], and the

The use of 4,4,4-trifluorothreonine to stabilize extended peptide structures and mimic β-strands

• Yaochun Xu,
• Isabelle Correia,
• Tap Ha-Duong,
• Nadjib Kihal,
• Jean-Louis Soulier,
• Julia Kaffy,
• Benoît Crousse,
• Olivier Lequin and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2017, 13, 2842–2853, doi:10.3762/bjoc.13.276

• in good yield starting from the N-benzylation of L-proline in the presence of KOH, then activation of the carboxylic acid functionality of 10 using SOCl2 at low temperature, followed by condensation with 2-aminobenzophenone (Scheme 2). Complexation of 11 with nickel nitrate and glycine under basic

Binding abilities of polyaminocyclodextrins: polarimetric investigations and biological assays

• Marco Russo,
• Daniele La Corte,
• Annalisa Pisciotta,
• Serena Riela,
• Rosa Alduina and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2751–2763, doi:10.3762/bjoc.13.271

• between our materials and polyanions were investigated by studying the binding with sodium alginate. Finally, the complexation abilities of the same materials towards polynucleotides were assessed by studying their interaction with the model plasmid pUC19. Our results positively highlight the ability of

• synthesis of noble metal nanoparticles, and systems for the complexation and cell transfection of genetic material [17][18][19][20][21][22]. In particular, the complexation and transfection of polynucleotides also have been successfully accomplished by means of polycationic cyclodextrin or calixarene

• preliminary investigation of the polarimetric behaviour of free AmCDs was a prerequisite before addressing their complexation abilities by means of polarimetry. Thus, the relevant molar optical rotations Θ were measured at different pH values, in order to study the possible effect of the progressive

Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2698–2709, doi:10.3762/bjoc.13.268

• constant. As we will discuss in detail later, complexation of substrates 1–12 with CAP leads in several cases to the formation of 2:1 complexes, either alone or together with the corresponding 1:1 complexes (as accounted for by the analysis of the relevant Job plots). In these cases, Equation 1 cannot be

Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of γ-cyclodextrin

• Markéta Bláhová,
• Sergey K. Filippov,
• Lubomír Kováčik,
• Jiří Horský,
• Simona Hybelbauerová,
• Zdenka Syrová,
• Tomáš Křížek and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2017, 13, 2509–2520, doi:10.3762/bjoc.13.248

• complexation of the alkylation agent to the CD cavity and orientation of the agent´s reactive center towards the 3-OH group [11][12][13]. Here, we report the preparation of regioisomers of novel mononaphthylallyl γ-CD (NA-CD), i.e., 3-(naphthalene-2-yl)prop-2-en-1-yl γ-CD, which is interesting for several

• were studied by a set of methods allowing characterization of supramolecular behavior at various levels – from binary complexation, over supramolecular oligomers to large assemblies; namely by isothermal titration calorimetry (ITC) [16], 1H nuclear magnetic resonance spectroscopy (1H NMR), dynamic

• absence of the significant concentration dependence of chemical shifts of the CD hydrogens does not disqualify inclusion complexation because changes of chemical shifts by 0.01 ppm or less were observed upon inclusion of an aromatic guest into the γ-CD cavity [41]. To reconcile the absence of interactions

Synthesis and photophysical properties of novel benzophospholo[3,2-b]indole derivatives

• Mio Matsumura,
• Mizuki Yamada,
• Atsuya Muranaka,
• Misae Kanai,
• Naoki Kakusawa,
• Daisuke Hashizume,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2017, 13, 2304–2309, doi:10.3762/bjoc.13.226

• , respectively. The reaction of 3 with methyl triflate afforded phospholium triflate 7. Phosphole 3 was treated with chloro(dimethyl sulfide)gold in CH2Cl2, resulting in P-complexation and thus affording the gold complex 8. The borane complex 9 was readily prepared from 3 by treating with borane in THF. The

Structural diversity in the host–guest complexes of the antifolate pemetrexed with native cyclodextrins: gas phase, solution and solid state studies

• Magdalena Ceborska,
• Magdalena Zimnicka,
• Aneta Aniela Kowalska,
• Kajetan Dąbrowa and
• Barbara Repeć

Beilstein J. Org. Chem. 2017, 13, 2252–2263, doi:10.3762/bjoc.13.222

• /bjoc.13.222 Abstract The complexation of the antifolate pemetrexed (PTX) with native cyclodextrins was studied. This process, along with the findings gathered for the structurally related folic acid was treated as a model for exploiting host–guest interactions of this class of guest molecules in the

• gas phase, in solution and in the solid state. Mass spectrometry was employed for the investigation of the architecture and relative gas-phase stabilities of these supramolecular complexes. The mode of complexation was further tracked by 1D and 2D NMR proving the formation of the exclusion-type

• interacts with hydroxy groups of the wider rim of α-CD (CD#OH2 and CD#OH3). Changes upon complexation are also seen for PTX#H1 while the chemical shift of amidic proton PTX#H2 does not change at all, suggesting the lack of any interactions with the host molecule. In addition, the obtained data suggests that

Superstructures with cyclodextrins: Chemistry and applications IV

• Gerhard Wenz

Beilstein J. Org. Chem. 2017, 13, 2157–2159, doi:10.3762/bjoc.13.215

• insulin and lysozyme were also conjugated to the guest adamantane. The complexation of these conjugates by pegylated β-CD gives rise to superstructures which provide slow release and maintain full biological activity [21]. Significant progress was also achieved in the field of CD rotaxanes. A [3]-rotaxane